1. Field of the Invention
The subject of the invention is a wheel, composed of a disc and a rim, for a tire, able possibly to form, with a support ring for the tread of the tire and the tire, a rolling assembly which may be useful in the case of running when the inflation pressure drops abnormally relative to the normal pressure of use, referred to as rated service pressure, which pressure may possibly even become zero.
2. Description of the Related Art
The main difficulties encountered in the case of running on a flat tire or at low pressure relate to the risk of unseating of the beads of the tire and in particular the unseating of the bead located on the outside of the tire mounted on the outside of the vehicle when cornering. The well-known proposed techniques for avoiding such unseating, and in particular the one consisting of arranging a protrusion or hump of low height axially to the inside of the outer rim seat, do not appear to be completely satisfactory and tend to increase the difficulties of mounting and dismounting the tires.
U.S. Pat. No. 6,470,936 (which is a counterpart to Application WO 00/05083) describes by way of example, in order to solve the above problem effectively, an integral wheel such as shown in FIG. 1A. This wheel has a radially outer geometry comprising a first and a second seat which are intended to receive a tire bead, at least the first seat having a generatrix, the axially outer end of which is on a circle of diameter less than the diameter of the circle on which the axially inner end is located, said seats being extended axially to the outside by a protrusion or “hump” of low height, the first seat being extended axially to the inside by a cylindrical surface intended to receive a tread support ring. This wheel is such that the cylindrical surface is formed of a first and a second zone which are separated by a circumferential groove which opens out radially externally. It may be produced by molding an aluminum alloy in a single operation.
The presence of the circumferential groove is intended to reduce the weight of the wheel significantly. This wheel, which is optimized in terms of weight, does however have the drawback, when the outer profile comprises a mounting groove for a tire, of permitting the accumulation, beneath the axially outer portion relative to the mounting groove of the inner profile of the rim of this wheel, of all sorts of materials, such as mud mixed to a greater or lesser extent with stones, such as snow or ice in winter conditions, which materials are difficult to evacuate.